97th DOG Annual Meeting 1999



M. Mrochen, P. Riedel, H. Petersen, T. Seiler

Pre-clinical investigations demonstrated the potential advantages of the Erbium:YAG laser vitrectomy for posterior segment surgery. However, a reliable knowledge about the laser-tissue interaction is needed for new ophthalmic applications. The aim of this experimental work was to investigate the vapor bubble formation during Erbium:YAG laser vitrectomy and to find optimized laser parameters, fiber tip geometries and ideal geometries of the microsurgery probe.

Materials and Methods: In water, the formation of the evaporation bubbles was investigated by high speed photography. The output energy at the quartz tip ranged up to 50 mJ and the laser pulse duration from 50 µs to 300 µs. Various quartz fiber tips and different microsurgery probes were investigated to minimize evaporation.

Results: The optimized laser pulse energy and the laser pulse duration for Erbium:YAG laser vitrectomy was found to be in the range of 3-10 mJ and 200 ┬Ás and more. The diameter of the quartz fiber tip should exceed 200 µs and the fiber tip should have a spherical shape. A slit form of the suction port (width 0,2-0,4 mm) was discovered as the best geometry of the aspiration port.

Conclusions: The optimized microsurgery probe geometries and laser parameters might decrease the risk of intra-operative ocular damages during Erbium:YAG laser vitrectomy.

University of Dresden; Department of Ophthalmology; Fetscherstr. 74; D-01307-Dresden; Germany